Device for actuating the needle bar of zig-zag sewing machines



April 28, 1959 G. AMMAN TUATING THE NEEDLE BAR OF ZIGTZAG SEWING MACHINES DEVICE FOR AC Filed March 24, 1955 3 Sheets-Sheet l 0 Q I mp FW 2 N 2 ON Q A mm N 7//. Q z &n N F r ///V AAA /Vvv v// v m v vv Inventor yiPAF flM/Mf By Z; z:

v Attorneys April 28, 1959 AMMAN 2,883,951

DEVICE FOR .ACTUATING THE 'LEEJDLE BAR OF ZIGZAG SEWING M ACHINES Filed. March 24, 1955 r I 3 Sheets-Sheet 2 k in Fig.

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In uenlor Attorneys United States Patent DEVICE FOR ACTUATING THE NEEDLE BAR OF ZIG-ZAG SEWING MACHINES Giuseppe Amman, Milan, Italy, assiguor to Fratelli Borletti D.p.a., Milan, Italy Application March 24, 1955, Serial No. 496,512

Claims priority, application Italy March 30, 1954 2 Claims. (Cl. 112-221) In zig-zag sewing machines the actuating unit swinging the needle bar usually comprises several universal joints and a slide which operate through a swinging rod to impart a side-to-side pendulum motion to the needle bar.

However, during operation of the machine play is likely to develop rapidly because of the wear of the frictionally contacting parts both in the universal joints and the slide, such play causing faulty positioning of the needle and spoiling the work.

This is a great disadvantage, for as the slide-bearing has only a limited contact surface with the slide, even a small amount of play between these two parts results in noticeable displacement of that end of the rod which is connected to the needle bar, and therefore, noticeable errors in the positioning of the bar.

The present invention relates to a device for actuating the needle bar of zig-zag sewing machines which tends to eliminate these disadvantages.

This device is characterized by the fact that linkages formed by springs connecting the means for supporting the needle bar and for longitudinally trailing the needle bar with respect to the parts in relation to which said means are subjected to small rotary oscillations during the double movement of transversal swinging and axial displacement of the needle bar, are associated with supporting means of the fork controlling the swinging of said bar, said means consisting of a slide movable in two interspaced holes.

By means of this arrangement, the frictionally engaged surfaces are reduced to a negligible minimum, thus practically avoiding the play causing the above mentioned errors in the positioning of the needle bar.

The invention will now be described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a longitudinal section of the arm of a zigzag sewing machine containing a needle bar which is adapted to swing like a pendulum about a horizontal axis, together with its actuating device.

Fig. 2 shows in plan view a detail of the mechanism for imparting the swinging movement of the needle bar.

Fig. 3 is a front view of the arm, partially in section showing the connection of the member trailing the needle bar in axial movement to the crank shaft actuating the said member.

Fig. 4 is a section through the broken line A-A of Fig. 1.

Fig. 5 shows in front view a modification of the mounting of a needle bar swinging about a vertical axis parallel thereto, and

Fig. 6 is a section about the line B-B of Fig. 5.

With reference to Figs. 1 to 4, a support 1 of a needle bar 2 is connected to the head of an arm 3 of the machine by means of a leaf spring 4, said spring being fixed to said support by means of a screw 5 and to said arm by means of a screw 6. At its lower end the support 1 is connected to a rod 7, the latter being adapted under 2,883,951 Patented .Apr. 28, 1959 Ice the action of a leaf spring 8 to swing said support from the position X-X to the position Y-Y and vice versa. The spring 8 is fixed to the support by means of a screw 9 and to the rod by means of screws 10 and 11. The

5 rod 7 receives its swinging movement in known manner from a stem 12' of a fork 12 to which it is fixed, said fork being actuated by a cam 13 fixed on a vertical shaft 14 driven by a main shaft 15 of the machine. The fork 12 has at its mid portion a cylindrical boss with a vertical hole therein. A pivot pin 18 parallel to camshaft 14 is journalled in the hole, and has therethrough a hole in which is positioned a slide rod 16. The boss of the fork has, in the sides thereof, oval holes 19 through which the slide rod 16 extends. This arrangement permits the fork to oscillate about the pivot pin 18, and thus it oscillates with respect to the longitudinal axis of the slide rod 16, also. A screw 18' secures the pivot pin 18 to the slide rod 16, and the slide rod 16 is supported near its ends in two spaced guiding elements 17, which define the axis Z-Z that is at an oblique angle to the line joining the centers of shaft 14 and pivot pin 18.

In operation, and assuming the parts are in the position shown in Figs. 1 and 2, rotation of shaft 14 will cause cam 13 to rotate also. This will give a combined rotary and translational movement to fork 12, which will rotate about pivot pin 18 and will also translate along axis ZZ, due to the fixing of pivot pin 18 (and fork 12) against longitudinal movement on slide bar 16. Slide bar 16, with pivot pin 18 and fork 12 fixed thereto against longitudinal movement, will slide in the guide elements 17. The combined rotary and translational movement of fork 12 will be transmitted by rod 7 to the needle bar 2.

A trailing member 20 connected by means of a spherical joint 21 to a ring 22 fixed to the needle bar 2 by means of a screw 23 imparts axial movement to the needle bar. The member 20 is connected to a crank pin 24 carried by the driving shaft 15 by means of a leaf spring 25 acting thus as a link, said spring being fixed by means of a screw 27 to the member 20 rotatably mounted on the pin 24 and acting as a link head.

In the embodiment shown in Figs. 5 and 6, a support 29 of a needle bar 30 is connected to an arm 31 of the sewing machine by means of two leaf springs 32 fixed to the support 29 by means of screws 33 and fixed to the arm 31 by means of screws 34. Thus, the support 29 can swing about a vertical axis parallel thereto, which intersects the axes of the two screws 34. The operation is otherwise the same as that described with reference to Figs. 1 to 4.

Of course, the invention comprises any possible modification of the constructional details of the embodiments shown, without going out of the scope of the invention.

Having described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A zig-zag sewing machine having an arm having a free end, a head carried by the free end of the arm, a main shaft horizontally mounted in said arm, a needle bar support, leaf spring means connected to said needle bar support and to the head for mounting the needle bar support in said head for lateral swinging movement relative to the head, a needle bar mounted in said needle bar support for axial reciprocation in a general vertical direction, a crank pin eccentrically carried by the main shaft, driving means carried by the needle bar for transmitting axial reciprocating motion thereto, a second leaf spring in the form of a connecting rod, means connecting one end of the second leaf spring to the driving means on the needle bar and means connecting the other end of the second leaf spring to the crank pin for transmitting rotary movement of the crank pin about the axis of the main shaft into axial reciprocating motion of the needle bar, a vertical cam shaft mounted in said arm and driven by the main shaft, a cam on the cam shaft, :1 link, a fork on one end of the link engaging the cam, a slide carried by the :fork, guide means carried by the arm for receiving the slide and transmitting transverse oscillations of the fork into axial oscillations of 'the link, and a third leaf spring connecting the other end of the link to the needle bar support for imparting oscillation of the link to the needle bar support.

2. A sewing machine according to claim 1 further comprising a boss carried by the fork and having an opening through which the slide extends, said opening being of oval cross section and the slide being of circular cross section to enable the fork and slide to have angular play between them.

References Cited in the file of this patent UNITED STATES PATENTS 572,039 Willcox Nov. 24, 1896 2,664,058 Amman Dec. 29, 1953 2,682,845 Robert et al July 6, 1954 E GN PA NTS 1,087,650 France Aug. 25, 1954 

